It’s hard to imagine Chicago without a Daley at the helm – a situation that has been the reality for fewer than 13 of the past 55 years. This Christmas, in fact, Mayor Daley will break the record his father, Richard J. Daley, set of 21 years in office.

“In the end this is a personal decision, no more, no less,” Daley said in his announcement at City Hall, where he appeared with his wife and adult children, saying he was “ready with my family to begin the new phase of our lives.” Simply put, he added, “it’s time for me, it’s time for Chicago to move on.”

But while his news stunned the political set both in Chicago and nationally, pundits are quickly scrambling to begin handicapping an election without Daley, who – despite occasional rumblings of corruption and falling approval ratings – has always been a virtual shoo-in.

Under Daley, Chicago has run like clockwork, thanks largely to his virtually monolithic control and a guaranteed rubber stamp from a compliant City Council, though many Chicagoans have chafed at his perceived dictatorship. In one famous (or infamous) Daley move, he was frustrated by the lack of momentum in his efforts to shut down the Meigs Field airstrip in the city and turn it into a park. So he sent bulldozers in during the middle of the night to gouge X’s across the field. He later justified his actions as motivated due to post-9/11 safety concerns.

Time magazine in 2005 named him the best big-city mayor in the country, and despite his connections to various scandals or rumors of corruption, Daley has largely enjoyed widespread popularity. During his last three elections he won with more than 70 percent of the vote. That has fallen lately, with a poll this summer showing him with just a 37 percent approval rating.

He’ll certainly be leaving a strong physical mark on the city he adores. Among the changes to Chicago that are directly attributable to Daley: Millennium Park, renovations to Navy Pier, the O’Hare Airport terminals, Soldier Field, and the rebuilding of State Street and Museum Campus. The city under Daley became greener, and sprouted “green roofs” – including at City Hall – and thousands more trees. Notorious public housing towers came down. And dozens of schools have been shuttered and reopened under his ambitious “Renaissance 2010” plan.

President Obama, a Chicago resident, said in a statement Tuesday: "No mayor in America has loved a city more or served a community with greater passion than Rich Daley. He helped build Chicago’s image as a world-class city, and leaves a legacy of progress that will be appreciated for generations to come."

One seeming certainty about the next mayor: It will be a Democrat. The last time Chicago elected a Republican mayor was when William Hale Thompson was elected in 1927.